You may have a benign (non cancerous) tumor.
I've had breast cancer (at 67 years old) but also craploads of little benign lumps since my 20's. I remember all the freak outs I had so wanted to respond to your concern over this.
In the area of cancer, it's great to have a second (and third) opinion. Unlike other areas of medicine, cancer is run by Big Pharma. Even the doctors aren't given all the facts and sometimes rush into things. Many lumps come & go naturally, actually. That said, if there is a thread of doctors who feel you should have a biopsy then I'd suggest doing it. All things (including biopsies) are invasive on the breast so you want to be more certain this is necessary. Try not to go the a dark place realizing most things are NOT cancerous. I had a tumor that was different than all my other lumps so had a biopsy and "lumpectomy" to remove it. They also removed 2 lymph nodes (that's all I'd allow) which were both "clear" ~ meaning the cancer hadn't spread to them (a concern with cancer). So you're WAY over the fence worrying at this point about jumping into the cancer diagnosis. Radiologists are great at spotting things, however. Remembering that like every other profession, there are a few great ones , a lot of average ones and some real slackers. Get opinions, then check your own opinion.